Approaches for providing various services to users of network-connected apparatuses, utilizing network technology, have been proposed and put to practical use. In a typical approach, a Web server and a data base accessible from the server are related to each other by a program running on the server side, the database is accessed using information input by the user, and the information to be presented to the user is output to a user terminal in HTML (HyperText Markup Language) or XML (eXtensible Markup Language) format.
In the present specification, such a service providing system that utilizes a program running on the server side will be referred to as a Web service.
In the Web service, it is necessary to form various HTML or XML documents in accordance with an input or a result of access to the database. Further, it is often the case that, depending on the service to be provided, screen of totally different formats must be formed even if related processes are almost the same, or screen impression must be consistent even if services are different. In the conventional Web service system, a portion describing the screen is embedded in a logic (program) portion for providing the service and, therefore, in such a case, modification such as a change to the screen only, or a change to the logic only while maintaining the screen intact is very difficult. Further, the conventional system also has a problem that program development on a so-called multiplatform is difficult.
Various methods have been proposed to solve these problems.
Patent Document 1 proposes a program generator for forming a source program to provide Web service. In this system, for forming the Web service, an XML program of a unique format describing attributes of items to be displayed on the screen and an HTML program controlling screen design are prepared as separate programs. The program generator converts the XML program and the HTML program to a source program to be usable on the Web, by adding general functions such as a log output function and a screen transition destination. According to the technique described in Patent Document 1, if only the screen design is to be changed, only the HTML program has to be changed. If only the display item is to be changed, only the XML program has to be changed. In either case, a source program in which only the screen design or only the display item is changed, can be obtained by activating the source program generator again.
Patent Document 2 discloses a display information fixing apparatus for substituting content to be embedded in a template. In the system, pieces of content specifying information are associated with a page template as an object of display. When the display conditions associated with each piece of content specifying information are fixed, the display information fixing apparatus substitutes the content to be embedded in the page template in accordance with the conditions. By this apparatus, various contents can be embedded in one same template depending on conditions and transmitted to the client, without modifying the server program. Therefore, the contents displayed on the client apparatus can dynamically be changed.    Patent Document 1: Japanese Patent Laying-Open No. 2002-366352    Patent Document 2: Japanese Patent Laying-Open No. 2001-51821